Compressors, such as an axial compressor, a centrifugal compressor, and a rotary compressor, often face problems with a reduction in working efficiency due to corrosions of the turbine blades used in the compressor system. Turbines are formed with stages of turbine blades, including rotor and stator blades. Efficiency tends to drop as the blades become corroded or fouled over time. The blades tend to collect deposits, such as iron oxide particulates and other oxide debris from the gases and fluids at the rear stages of the compressor turbine. Deterioration of blade surfaces due to fluids and gases during operation, and/or reactions with particulate deposits may be rapid. Such surface damages may not easily be removed by water wash because the deposits may not be water soluble.
It is well known in the industry that deterioration can be reduced by protecting the blade surfaces using a number of coating techniques. For instance, blade surfaces are known to be protected through pure coating on the blade. U.S. App. No. 2007/0261965 describes a composition and method to provide a coated object that has a high-temperature resistance. The coated object is produced by electrodeposition of one or more metal or metal alloy layers on a substrate and thermal treating the coated substrate such that the layers and the substrate partially and/or completely interdiffuse.
It is believed that, due to the potential corrosive and erosive working environment for a turbine blade, application of a hard, oxidation resistant coating may be desirable. In addition, down-time conditions in a compressor may result in possible moisture condensation in a corrosive environment to further enhance the deterioration of the blade surface. Known solutions to the problem include discussions in U.S. Patent App. Pub. No. 2009/0297720 and 2011/0165433.